email to sms gateway spam filter issue with multiple domain

Thanks for sharing that resource @BobT! As I said on your other post, @nwtotalatm, the spam filters on the email to text gateway are pretty strict and whitelisting is not an option because email to text is not designed for business purposes. The messages that you are sending are not considered consumer to consumer messages and should be sent through message aggregators or other similar services to ensure that they are complying with all proper guidelines and are not flagged as spam. As you can see from the ticket that you had submitted, we can offer temporary relief by telling the system that you are not spam, but you will be flagged again if you continue to send messages the same way. 

On the other post you mention getting your situation to our admin of the spam filtering and I have discussed this situation with that team many times and the answer is always the same. The option to whitelist is not available and all non-consumer messaging should be done through the proper channels. Those aggregation systems exist to protect companies from getting blocked as spam and ensure that all communication guidelines are being followed. They also protect customers from receiving unwanted messages by allowing them to opt in and out of messages from the sending company.

I understand that your messages are going to your employees and not general public, but the concept is still the same. If you are uncomfortable with the message aggregation options, you can also send those notifications to your techs' emails instead of phone numbers, or even look at options for creating an app that they can download to get necessary notifications. 

You will need to reach out to T-Mobile Support and have them verify and whitelist your business domain.